[scalbert]

In the process of another Mr.5 intake install and wanted to look into a few matters. I'll actually be trying out a redesign to the lid, ala Dinan, as well as a modified lower section. Lower section first though as it is easier; the tubing and bellmouth are on order.

But I wanted to try and determine the actual restriction of the stock box when running higher boost. We know that the DCI's have no box and the size of the tubing going to the turbo is the same regardless. So there were three points where the flow could be restricted; inlet flow path sizes, inlet flow path restrictions and/or filter area.

The box inlet measured to 10.31 square inches
The lid outlet measures about 9 square inches

Considering the tubing to each turbo at the junction to the DCI's or stock box is only 8.0 square inches for both in total, the ducts are not the problem.

One possibility is with the flow path its self. The multiple 90 and 180 degree turns are never good for flow. But consider that more than ample volume; it probably isn't the greatest contributor.

That leaves filer area. One thing I did not measure out was the true pleat area as I didn't feel like counting. But most would agree that the stock filter does not use the majority of its area which can be seen with an inspection. So comparing areas:

Stock, 85 square inches
DCI, 150 square inches (75 * 2 filters)

The DCI has 76% more filter area and is most likely the source for the limitation. Now, keep the stock box and add Mr.5’s intake method and you get 160 square inches if using a DCI filter. In looking at size piping, I see no need to go larger than 2.25 inches ID if using a smooth wall. That is what the DCI’s have to work with.

Just a thought…

[huyner328]

Areas like the plastic crap tubing, 8 and 13 seem restrictive.

[scalbert]

Originally Posted by huyner328

Areas like the plastic crap tubing between 1 and 13 seem restrictive. As well as 8.

It was a comparison of the actual intakes available. Those restriction you cite, and agree are restrictions, are the same regardless of stock, DCI, etc.

[Mr. 5]

Great thread.
I did notice a difference when going from a 2" opening to a 3" opening and I believe your point about the 2.25" opening is valid but the key ingredient that you mentioned is that if it's 2.25 all the way through and smooth.
It was a lot harder to find solid pieces in increments of .25" and it was a lot easier to find tubing in 3" ID.
Also, another thing to note is that the ID of the DCI filters are 3" so it was nice to have 3" the entire way.

[R1000K3]

2.25 may be to small, a 2.5 or 3" hose help flow a lot in the 90 degree turn section down the airbox.

[scalbert]

Originally Posted by Mr. 5

Great thread.
I did notice a difference when going from a 2" opening to a 3" opening and I believe your point about the 2.25" opening is valid but the key ingredient that you mentioned is that if it's 2.25 all the way through and smooth.
It was a lot harder to find solid pieces in increments of .25" and it was a lot easier to find tubing in 3" ID.
Also, another thing to note is that the ID of the DCI filters are 3" so it was nice to have 3" the entire way.

I would go with 3.0 all the way but was also trying to make the hose install as easy as possible and with no modifications to any factory parts such as the mount for the steering fluid resevoir. We'll see though and I can alway go bigger if needed. I have three feet of 2.25 inch silicon tubing on the way now.

[Mike@N54Tuning.com]

I've been told a big problem is the flow path in to the stock plenum. If you take a stock size filter and duct tape it to cone of card board, then duct tape that cone to the stock plenum/belmouths you can achieve DCI like performance. This led to a lid redesign that showed some gains but not enough to justify mass production.

Mike

[scalbert]

Originally Posted by Mike@N54Tuning.com

I've been told a big problem is the flow path in to the stock plenum. If you take a stock size filter and duct tape it to cone of card board, then duct tape that cone to the stock plenum/belmouths you can achieve DCI like performance. This led to a lid redesign that showed some gains but not enough to justify mass production.

In either case, you would most likely use the majority of the filter area. My belief is, and due to the dirt patterns on the stock filter, that only a portion of it is used. This further exacerbates the issue with filter area.

Again, just a hypothesis.